1. Field of the Invention
The present invention relates to synchro drive systems including the type which are used in cockpit display devices.
2. Description of the Prior Art
It is known in the art that direct synchro load receivers ("synchronous drive") may exhibit uncontrolled spin, instability or other undesirable oscillatory behavior when subjected to large angle commands from an electronic digital to synchro converter ("D/S converter").
The primary reason for such instability in the synchro drive is a consequence of the saturation characteristics of the D/S converter, which typically has a saturation threshold which is equal to about 15.degree. of angular input. Such instability is unacceptable since a steady state value is never achieved.
One approach to reduce the occurrence of instability of the synchro is to decrease the power available to drive the synchro; this however results in a slower rate of response and reduced accuracy of the display device as the reduced drive power will be insufficient to allow for a rapid response to be displayed or indicated by the synchro as a function of the input signal also known as the digital angle command signal. Further, there is a loss of resolution in the output display of the synchro as the reduced power available reduces the accuracy of the indication.
An alternate method to reduce the occurrences of uncontrolled spin, instability, or other undesirable oscillation is to introduce a mechanical and/or fluid damping system into the synchro. Such a system would include the moving mechanical elements of the synchro drive and due to the viscous effects of the fluid, limits the rate of response of the synchro drive. Such a system is also undesirable as it is complex to fabricate, and further, causes a lag in the response of the synchro drive.
Accordingly, there is a continuing need in the art for improved direct synchro drive stabilization systems.